Astronomer Calvin Leung was excited last summer to crunch data from a newly commissioned radio telescope to precisely pinpoint the origin of repeated bursts of intense radio waves—so-called fast radio bursts (FRBs)—emanating from somewhere in the northern constellation Ursa Minor.
Leung, a co-author of both papers, is a lead developer of three companion telescopes—so-called outriggers—to the original CHIME radio array located near Penticton, British Columbia.
New CHIME outrigger in California A third outrigger radio array will go online this week at Hat Creek Observatory, a facility in Northern California formerly owned and operated by UC Berkeley and now managed by the SETI Institute in Mountain View.
“The source could be in a globular cluster, a dense region of old, dead stars outside the galaxy.
If confirmed, it would make FRB 20240209A only the second FRB linked to a globular cluster.”
Last summer, astronomer Calvin Leung was eager to analyze data from a recently commissioned radio telescope in order to determine the exact location of recurrent bursts of powerful radio waves, known as fast radio bursts (FRBs), that were coming from somewhere in the northern constellation Ursa Minor.
Leung, who received a Miller Postdoctoral Fellowship at the University of California, Berkeley, aspires to one day comprehend the causes of these enigmatic explosions and utilize them as probes to track the universe’s large-scale structure, which is essential to its formation and development. At arm’s length, he had written the majority of the computer code that enabled him and his associates to triangulate the location of a burst to within a hair’s width by combining data from multiple telescopes.
When his coworkers on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) immediately turned optical telescopes, the excitement turned to confusion when they learned that the source was located in the far-off periphery of a long-dead elliptical galaxy, which by all rights shouldn’t have the type of star believed to be responsible for these bursts.
Leung stated that rather than discovering the anticipated “magnetar”—a spinning neutron star that is highly magnetized and left over from the core collapse of a young, massive star—”now the question was: How are you going to explain the presence of a magnetar inside this old, dead galaxy?”.
These millisecond radio wave bursts are thought to be produced by young stellar remnants that should have vanished long ago in the 11point-3-billion-year-old galaxy, which is 2 billion light years away from Earth and has a mass greater than 100 billion times that of the sun.
In addition to being the first FRB discovered outside of a dead galaxy, this one is also the furthest from the galaxy it is associated with. Leung’s initial calculations regarding the location of the burst, known as FRB 20240209A, were refined and expanded by Vishwangi Shah, a doctoral student at McGill University in Montreal, Canada. “The FRB’s location is surprising and raises questions about how such energetic events can occur in regions where no new stars are forming,” Shah said.
Shah and colleagues from Northwestern University in Evanston, Illinois, co-authored a study of the FRB that was published in Astrophysical Journal Letters, with Shah serving as the corresponding author.
Leung is a co-author of both papers and the principal developer of three outriggers, or companion telescopes, to the original CHIME radio array near Penticton, British Columbia. He served as Shah’s mentor at McGill when Leung was a doctoral student at MIT. Before receiving his Miller fellowship, he held an Einstein Postdoctoral Fellowship at UC Berkeley.
California’s newest CHIME outrigger.
The SETI Institute in Mountain View, which currently oversees Hat Creek Observatory, a facility in Northern California that was once owned and run by UC Berkeley, will bring a third outrigger radio array online this week. The four arrays working together will significantly enhance CHIME’s capacity to locate FRBs with accuracy.
“We should be able to precisely pinpoint one FRB per day to its galaxy when paired with the three outriggers, which is substantial,” Leung stated. With two outrigger arrays, that is 20 times more effective than CHIME. “.
With this new accuracy, optical telescopes can turn to determine the kind of star groups that cause the bursts, such as spiral galaxies or globular clusters, and hopefully pinpoint the stellar source. It has been difficult to determine whether magnetars or any other kind of star are the source because few of the 5,000 or so sources that have been found so far—more than 95% of which were found by CHIME—have been linked to a particular galaxy.
Shah increased the pinpointing accuracy offered by the CHIME array and one outrigger array in British Columbia by averaging numerous bursts from the repeating FRB, as explained in the recently published paper. Astronomers documented 21 additional bursts through July 31 following its discovery in February 2024. Shion Andrew at MIT has added information from a second outrigger at the Green Bank Observatory in West Virginia since the paper was submitted, confirming Shah’s published position with 20 times the accuracy.
Shah stated, “This result challenges existing theories that tie FRB origins to phenomena in star-forming galaxies,”. “A dense area of old, dead stars outside the galaxy called a globular cluster could be the source. Should this be verified, FRB 20240209A would be the only other FRB associated with a globular cluster. “.
She pointed out that the other FRB, which came from a globular cluster, was linked to a living galaxy rather than an ancient elliptical where star formation had stopped billions of years ago.
“There’s still a lot of exciting discovery space when it comes to FRBs and that their environments could hold the key to unlocking their secrets,” said Tarraneh Eftekhari, the second paper’s first author and recipient of an Einstein Postdoctoral Fellowship at Northwestern.